1//===- llvm/ADT/ilist_node.h - Intrusive Linked List Helper -----*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines the ilist_node class template, which is a convenient
10// base class for creating classes that can be used with ilists.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_ILIST_NODE_H
15#define LLVM_ADT_ILIST_NODE_H
16
17#include "llvm/ADT/ilist_node_base.h"
18#include "llvm/ADT/ilist_node_options.h"
19
20namespace llvm {
21
22namespace ilist_detail {
23
24struct NodeAccess;
25
26} // end namespace ilist_detail
27
28template <class OptionsT, bool IsReverse, bool IsConst> class ilist_iterator;
29template <class OptionsT> class ilist_sentinel;
30
31/// Implementation for an ilist node.
32///
33/// Templated on an appropriate \a ilist_detail::node_options, usually computed
34/// by \a ilist_detail::compute_node_options.
35///
36/// This is a wrapper around \a ilist_node_base whose main purpose is to
37/// provide type safety: you can't insert nodes of \a ilist_node_impl into the
38/// wrong \a simple_ilist or \a iplist.
39template <class OptionsT> class ilist_node_impl : OptionsT::node_base_type {
40 using value_type = typename OptionsT::value_type;
41 using node_base_type = typename OptionsT::node_base_type;
42 using list_base_type = typename OptionsT::list_base_type;
43
44 friend typename OptionsT::list_base_type;
45 friend struct ilist_detail::NodeAccess;
46 friend class ilist_sentinel<OptionsT>;
47 friend class ilist_iterator<OptionsT, false, false>;
48 friend class ilist_iterator<OptionsT, false, true>;
49 friend class ilist_iterator<OptionsT, true, false>;
50 friend class ilist_iterator<OptionsT, true, true>;
51
52protected:
53 using self_iterator = ilist_iterator<OptionsT, false, false>;
54 using const_self_iterator = ilist_iterator<OptionsT, false, true>;
55 using reverse_self_iterator = ilist_iterator<OptionsT, true, false>;
56 using const_reverse_self_iterator = ilist_iterator<OptionsT, true, true>;
57
58 ilist_node_impl() = default;
59
60private:
61 ilist_node_impl *getPrev() {
62 return static_cast<ilist_node_impl *>(node_base_type::getPrev());
63 }
64
65 ilist_node_impl *getNext() {
66 return static_cast<ilist_node_impl *>(node_base_type::getNext());
67 }
68
69 const ilist_node_impl *getPrev() const {
70 return static_cast<ilist_node_impl *>(node_base_type::getPrev());
71 }
72
73 const ilist_node_impl *getNext() const {
74 return static_cast<ilist_node_impl *>(node_base_type::getNext());
75 }
76
77 void setPrev(ilist_node_impl *N) { node_base_type::setPrev(N); }
78 void setNext(ilist_node_impl *N) { node_base_type::setNext(N); }
79
80public:
81 self_iterator getIterator() { return self_iterator(*this); }
82 const_self_iterator getIterator() const { return const_self_iterator(*this); }
83
84 reverse_self_iterator getReverseIterator() {
85 return reverse_self_iterator(*this);
86 }
87
88 const_reverse_self_iterator getReverseIterator() const {
89 return const_reverse_self_iterator(*this);
90 }
91
92 // Under-approximation, but always available for assertions.
93 using node_base_type::isKnownSentinel;
94
95 /// Check whether this is the sentinel node.
96 ///
97 /// This requires sentinel tracking to be explicitly enabled. Use the
98 /// ilist_sentinel_tracking<true> option to get this API.
99 bool isSentinel() const {
100 static_assert(OptionsT::is_sentinel_tracking_explicit,
101 "Use ilist_sentinel_tracking<true> to enable isSentinel()");
102 return node_base_type::isSentinel();
103 }
104};
105
106/// An intrusive list node.
107///
108/// A base class to enable membership in intrusive lists, including \a
109/// simple_ilist, \a iplist, and \a ilist. The first template parameter is the
110/// \a value_type for the list.
111///
112/// An ilist node can be configured with compile-time options to change
113/// behaviour and/or add API.
114///
115/// By default, an \a ilist_node knows whether it is the list sentinel (an
116/// instance of \a ilist_sentinel) if and only if
117/// LLVM_ENABLE_ABI_BREAKING_CHECKS. The function \a isKnownSentinel() always
118/// returns \c false tracking is off. Sentinel tracking steals a bit from the
119/// "prev" link, which adds a mask operation when decrementing an iterator, but
120/// enables bug-finding assertions in \a ilist_iterator.
121///
122/// To turn sentinel tracking on all the time, pass in the
123/// ilist_sentinel_tracking<true> template parameter. This also enables the \a
124/// isSentinel() function. The same option must be passed to the intrusive
125/// list. (ilist_sentinel_tracking<false> turns sentinel tracking off all the
126/// time.)
127///
128/// A type can inherit from ilist_node multiple times by passing in different
129/// \a ilist_tag options. This allows a single instance to be inserted into
130/// multiple lists simultaneously, where each list is given the same tag.
131///
132/// \example
133/// struct A {};
134/// struct B {};
135/// struct N : ilist_node<N, ilist_tag<A>>, ilist_node<N, ilist_tag<B>> {};
136///
137/// void foo() {
138/// simple_ilist<N, ilist_tag<A>> ListA;
139/// simple_ilist<N, ilist_tag<B>> ListB;
140/// N N1;
141/// ListA.push_back(N1);
142/// ListB.push_back(N1);
143/// }
144/// \endexample
145///
146/// See \a is_valid_option for steps on adding a new option.
147template <class T, class... Options>
148class ilist_node
149 : public ilist_node_impl<
150 typename ilist_detail::compute_node_options<T, Options...>::type> {
151 static_assert(ilist_detail::check_options<Options...>::value,
152 "Unrecognized node option!");
153};
154
155namespace ilist_detail {
156
157/// An access class for ilist_node private API.
158///
159/// This gives access to the private parts of ilist nodes. Nodes for an ilist
160/// should friend this class if they inherit privately from ilist_node.
161///
162/// Using this class outside of the ilist implementation is unsupported.
163struct NodeAccess {
164protected:
165 template <class OptionsT>
166 static ilist_node_impl<OptionsT> *getNodePtr(typename OptionsT::pointer N) {
167 return N;
168 }
169
170 template <class OptionsT>
171 static const ilist_node_impl<OptionsT> *
172 getNodePtr(typename OptionsT::const_pointer N) {
173 return N;
174 }
175
176 template <class OptionsT>
177 static typename OptionsT::pointer getValuePtr(ilist_node_impl<OptionsT> *N) {
178 return static_cast<typename OptionsT::pointer>(N);
179 }
180
181 template <class OptionsT>
182 static typename OptionsT::const_pointer
183 getValuePtr(const ilist_node_impl<OptionsT> *N) {
184 return static_cast<typename OptionsT::const_pointer>(N);
185 }
186
187 template <class OptionsT>
188 static ilist_node_impl<OptionsT> *getPrev(ilist_node_impl<OptionsT> &N) {
189 return N.getPrev();
190 }
191
192 template <class OptionsT>
193 static ilist_node_impl<OptionsT> *getNext(ilist_node_impl<OptionsT> &N) {
194 return N.getNext();
195 }
196
197 template <class OptionsT>
198 static const ilist_node_impl<OptionsT> *
199 getPrev(const ilist_node_impl<OptionsT> &N) {
200 return N.getPrev();
201 }
202
203 template <class OptionsT>
204 static const ilist_node_impl<OptionsT> *
205 getNext(const ilist_node_impl<OptionsT> &N) {
206 return N.getNext();
207 }
208};
209
210template <class OptionsT> struct SpecificNodeAccess : NodeAccess {
211protected:
212 using pointer = typename OptionsT::pointer;
213 using const_pointer = typename OptionsT::const_pointer;
214 using node_type = ilist_node_impl<OptionsT>;
215
216 static node_type *getNodePtr(pointer N) {
217 return NodeAccess::getNodePtr<OptionsT>(N);
218 }
219
220 static const node_type *getNodePtr(const_pointer N) {
221 return NodeAccess::getNodePtr<OptionsT>(N);
222 }
223
224 static pointer getValuePtr(node_type *N) {
225 return NodeAccess::getValuePtr<OptionsT>(N);
226 }
227
228 static const_pointer getValuePtr(const node_type *N) {
229 return NodeAccess::getValuePtr<OptionsT>(N);
230 }
231};
232
233} // end namespace ilist_detail
234
235template <class OptionsT>
236class ilist_sentinel : public ilist_node_impl<OptionsT> {
237public:
238 ilist_sentinel() {
239 this->initializeSentinel();
240 reset();
241 }
242
243 void reset() {
244 this->setPrev(this);
245 this->setNext(this);
246 }
247
248 bool empty() const { return this == this->getPrev(); }
249};
250
251/// An ilist node that can access its parent list.
252///
253/// Requires \c NodeTy to have \a getParent() to find the parent node, and the
254/// \c ParentTy to have \a getSublistAccess() to get a reference to the list.
255template <typename NodeTy, typename ParentTy, class... Options>
256class ilist_node_with_parent : public ilist_node<NodeTy, Options...> {
257protected:
258 ilist_node_with_parent() = default;
259
260private:
261 /// Forward to NodeTy::getParent().
262 ///
263 /// Note: do not use the name "getParent()". We want a compile error
264 /// (instead of recursion) when the subclass fails to implement \a
265 /// getParent().
266 const ParentTy *getNodeParent() const {
267 return static_cast<const NodeTy *>(this)->getParent();
268 }
269
270public:
271 /// @name Adjacent Node Accessors
272 /// @{
273 /// Get the previous node, or \c nullptr for the list head.
274 NodeTy *getPrevNode() {
275 // Should be separated to a reused function, but then we couldn't use auto
276 // (and would need the type of the list).
277 const auto &List =
278 getNodeParent()->*(ParentTy::getSublistAccess((NodeTy *)nullptr));
279 return List.getPrevNode(*static_cast<NodeTy *>(this));
280 }
281
282 /// Get the previous node, or \c nullptr for the list head.
283 const NodeTy *getPrevNode() const {
284 return const_cast<ilist_node_with_parent *>(this)->getPrevNode();
285 }
286
287 /// Get the next node, or \c nullptr for the list tail.
288 NodeTy *getNextNode() {
289 // Should be separated to a reused function, but then we couldn't use auto
290 // (and would need the type of the list).
291 const auto &List =
292 getNodeParent()->*(ParentTy::getSublistAccess((NodeTy *)nullptr));
293 return List.getNextNode(*static_cast<NodeTy *>(this));
294 }
295
296 /// Get the next node, or \c nullptr for the list tail.
297 const NodeTy *getNextNode() const {
298 return const_cast<ilist_node_with_parent *>(this)->getNextNode();
299 }
300 /// @}
301};
302
303} // end namespace llvm
304
305#endif // LLVM_ADT_ILIST_NODE_H
306